1. Field of the Invention
The present invention relates to a substrate for photosensitive member, a photosensitive member, a production method thereof and an image forming apparatus using the same.
2. Description of the Prior Art
Electrophotography has made good progress in the area of copying machines, and has recently rapidly gained popularity because of good characteristic features it can provide, such as high image quality, high speed processing, and quiet operation, which are of such a high level as is beyond comparison with the prior art. More particularly, with remarkable progress made in the area of data processing systems for digital signals, laser beam printers, digital copying machines, and the like have been receiving high attention. Image forming methods which have been employed in such apparatuses include not only those adopting conventional regular development system such that an image is formed by causing toner to adhere to a portion other than portions irradiated with a light beam, but also methods of a reversal development system designed for effective light beam utilization and/or resolving-power improvement such that toner is caused to adhere to portions irradiated with light beams, such as laser beams, for image formation.
Photosensitive members used in aforesaid electrophotographic apparatuses generally comprise a substrate of such electrically conductive material as aluminum or aluminum alloy, and a photosensitive layer formed on the substrate. For the photosensitive layer a functionally separated lamination type layer structure is widely used such that a charge generating layer and a charge transporting layer are sequentially placed on an electrically conductive substrate. Such a photosensitive member involves a problem such that charge injection from the conductive substrate into the charge generating layer may occur at the stage of development, resulting in image noise troubles, that is, so-called black spots such that a toner image is formed at a spot at which any toner image is not to be formed, and/or so-called white spots such that no toner image is formed at a spot at which a toner image is required to be formed. For preventing the occurrence of such a trouble, it is general practice to provide an anodized layer by anodizing the surface of the substrate. However, with a photosensitive layer formed on such a substrate having an anodized layer, the trouble is that no smooth transfer of electrical charge from the photosensitive layer to the anodized layer could be achieved. As a consequence, the characteristics of the photosensitive layer are adversely affected. Furthermore, because of an increase in the surface area of the substrate due to the anodizing treatment, impurities in the treatment liquid or cleaning fluid may deposit on the substrate, resulting in a recurrence of the problem of black spots and/or white spots.
In such situation, U.S. Pat. No. 4,800,144 gives a teaching that an anodized surface of the photoreceptor substrate is subjected to sealing treatment with an aqueous solution of nickel acetate at a temperature of 50 to 80.degree. C. Japanese Patent Application Laid-Open No. Sho 63-214759 discloses a method in which an anodized surface of the photoreceptor substrate is subjected to sealing treatment with an aqueous solution of nickel fluoride at a temperature of 25 to 40.degree. C. In Japanese Patent Application Laid-Open No. Sho 63-311260 there is given a teaching that an anodized surface of the photoreceptor substrate is subjected to low-temperature sealing with an aqueous solution of red prussiate or the like at 40.degree. C. or less. However, in these methods, sealing treatment is made in one stage only; as such, the foregoing problem has not been completely solved.